Question

The total number of species from the following in which one unpaired electron is present, is ____.
\[ \text{N}_2, \text{O}_2, \text{C}_2^{-}, \text{O}_2^{-}, \text{H}_2^{+}, \text{CN}^{-}, \text{He}_2^{+} \]

Answer 1

Correct Answer: 4

Step 1: Analyze each species for unpaired electrons

1. N\(_2\): All electrons are paired.
2. O\(_2\): Two unpaired electrons are present in antibonding orbitals.
3. C\(_2^-\): One unpaired electron is present.
4. O\(_2^-\): One unpaired electron is present.
5. H\(_2^+\): One unpaired electron is present.
6. CN\(^-\): All electrons are paired.
7. He\(_2^+\): One unpaired electron is present.

Step 2: Count the species with one unpaired electron

Species with one unpaired electron:

\[ C_2^-, \, O_2^-, \, H_2^+, \, He_2^+. \]

Total number = 4.

Thus, the correct Answer is 4.